A gas turbine engine may be used to power aircraft or various other types of vehicles and systems. The engine typically includes a compressor that receives and compresses an incoming gas such as air; a combustion chamber in which the compressed gas is mixed with fuel and burned to produce exhaust gas; and one or more turbines that extract energy from the high-pressure, high-velocity exhaust gas exiting the combustion chamber.
A gas turbine engine typically further includes an engine control system, which as used herein refers to a system that serves in particular to control the operating speed of the turbine engine. By way of example, the engine control system controls the flow rate of air passing through the turbine engine, the flow rate of fuel into the combustion chamber, etc. A known example of an engine control system is shown in FIG. 1. The engine control system is fitted to a turbine engine having a main fuel circuit 12 including: a low pressure pump 16 connected to a fuel tank 14; a heat exchanger 17; a high pressure pump 18; and a hydro-mechanical unit (HMU) 19. The low pressure and high pressure pumps 16 and 18 are mechanically driven by an accessory gearbox 22 of the turbine engine. The high pressure pump 18 feeds the fuel injectors of the combustion chamber 20 of the turbine engine via the HMU 19. This HMU 19 serves in particular to measure out the fuel needed by the combustion chamber 20, and to return excess fuel to the main circuit 12 upstream from the heat exchanger 17 via a recirculation loop 21.
As part of the assembly provided to allow the HMU 19 to measure fuel, the HMU 19 includes a bypass valve 30, shown in cross-section in FIG. 2. Briefly, an exemplary bypass valve 30 includes an integrator valve 32 and a proportional valve 36. The integrator valve 32 includes an integrator spring assembly 34, and the proportional valve 36 includes a proportional spring 35. The bypass valve further includes a cover 33 surrounding the integrator spring assembly 34, and a sleeve 31 surrounding the proportional spring 35. The integrator spring assembly 34 anti-rotates the integrator valve 32 so as to prevent the introduction of wear debris in the assembly, and to further prevent fractures of the spring assembly 34.
Despite the anti-rotated design of the integrator valve 32, it is hypothesized that, in some rare instances, twisting of the integrator spring assembly 34 in the integrator valve 32 may result in pre-mature wear and/or fracturing of the spring assembly 34. Wear and/or fracturing of the spring assembly 34 could result in degraded performance and/or malfunctioning of the bypass valve 30. Accordingly, it is desirable to provide an improved bypass valve assembly, and in particular an improved integrator spring assembly, that further reduces the likelihood of pre-mature wear and/or fracturing of the integrator spring assembly. It is further desirable to provide methods for the production of such assemblies. Furthermore, other desirable features and characteristics of the invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.